I have a 87 camaro that came from the factory with the LG4. That motor is long gone and I have my 305 TBI from my 92 RS in it now. What I would like to know is if the LG4 in tank electric pump puts out enough PSI to run my TBI engine correctly. I remember reading somewhere that the LG4 used 2 pumps, 1 electric in tank and 1 mechanical on the block. My TBI has a block off plate where the mechanical one would go, so I only have the electric pump that came with the LG4 motor.

Does anybody know what PSI the in tank LG4 electric pump puts out? And if that pump doesn't put out enough, can I do the same thing that GM did with the LG4 and run a mechanical pump as well to attain the proper PSI to run my TBI engine? I ask this becasue I really don't want to drop that tank again to install a TBI pump if I don't have to.

Thanks

 

ummm you positive that there are 2 pumps? I had an LG4 (pulled it over a year ago) and have been running just a mechanical pump since then. I've never heard of a second pump in-tank for these motors

 

I know this car was a LG4 from the factory, and when I had droped the tank I saw an electric fuel pump. At that time I figured that since carbs and TBI run about the same pressure I would be fine to just use that pump.

Now I look into a factory service manual and it states that there are 2 fuel pumps and that the one in the tank is 3 PSI. Since the LG4 motor is long gone, I don't know if it had a mechanical pump as well on it. Does anybody know or can confirm that this electric in tank pump puts out only 3 PSI? or if I can do the same thing as the LG4 and also stick a mechanical pump to get the needed pressure to run my TBI motor?

Thanks

 

I know you need something like 19+ PSI to run your TBI, ANYTHING and I mean ANYTHING less than that and your car will not run or start. Had a Chevrolet pickup 88 that had a TBI and a 34 gal tank, every time I ran out of gas one the same pump at least 3 times it would burn up the pump. the pump would pump but only like 14 or 15 lbs. and the truck would not run, drop the tank install a new pump and viola it ran. after the second time of that I dropped the tank installed a sock with a pickup tube at the end of the sending unit and put in a inline pump, then I never ever needed to drop the tank again. A radiator shop can help you weld a pickup tube on the sending unit where the pump used to be. just cut the tube off at the same length as the pump or an inch shorter and install a sock filter.

 

I've never heard of an intank pump pre88. Unless your car was an unlucky GM test dummy or something. LG4's are supposed to run on a mechanical pump. Nothing fancy about these motors, they didn't have massive fuel requirements. Mine has it right on the pass side of the block. I know because it took a crap on me and I swapped it out. I don't see why there would be a second pump, unless someone put a newer tank on your ride. Just a thought

Will